The present invention relates to a compound axle assembly having two or more wheel axles for trailers, the wheel axles of which are supported by longitudinal guide means and are spring-suspended by pairs of leaf type springs, the central portions of which are connected to the axle bodies. The respectively outer ends of the leaf type springs are slidingly supported in brackets that are secured to the chassis of a vehicle, while the facing ends of the leaf type springs are slidingly supported on a compensating arm that is pivotably mounted in a bracket secured to the vehicle chassis.
A compound axle assembly of the aforementioned general type is known from German Patent 27 41 250. Steiner dated Jan. 27, 1983, belonging to the assignee of the present invention. With this heretofore known compound axle assembly, the ends of the leaf type springs are slidingly supported in the brackets that are secured to the chassis and in the compensating arms against sliding elements, and are not anchored to their supports by formed-on eyes or the like. As a result, during driving operation the ends of the leaf type springs can lift away from their sliding elements. When these spring ends return they strike the sliding elements, producing considerable clattering noises; this occurs in particular when the vehicle is empty. In order to counteract this clattering, it was proposed in German Gebrauchsmuster 73 13 196 Sauer dated Sept. 20, 1973 to associate with each support spring an expanding spring that is clamped against the axle together with the support spring. The ends of the expanding spring press against seats in the brackets, or with compound axle assemblies in the compensating arms thereof, in order to prevent the ends of the support springs from lifting away from their sliding elements. For this purpose, it is known from German Offenlegungsschrift 31 51 052 Steiner dated Aug. 4, 1983, belonging to the assignee of the present invention, to dispose in each compensating arm a spring that presses those ends of the support springs that extend into the compensating arms against their sliding elements under initial tension.
The heretofore known springs for preventing and damping the clattering noises are very expensive. For this reason, it was already proposed in U.S. Pat. No. 3,799,562 Hinchliff dated Nov. 26, 1974 to replace the springs by less expensive rubber rollers that are secured in the brackets or compensating arms below the ends of the support springs. However, in compound axle assemblies this less expensive approach is satisfactory only in the fixed brackets, because there the relative movements between the ends of the leaf type springs and their sliding elements for the rubber rollers are relatively small. In contrast, in the compensating arms the rubber rollers are very rapidly squashed during severe deflections, and hence become incapable of functioning.
Finally, German Offenlegungsschrift 22 16 018 Wende dated Oct. 11, 1973 discloses yet another means for supporting a leaf type spring on the chassis of a commercial vehicle. Here the spring end is mounted between two support bodies, the lower one of which is a cylindrical roller, and the upper one of which is a pendulum mounted, segmented cylindrical roller member, with a portion of its curved surface resting against the upper side of the spring end. Although with this mounting the pendulum mounted support body can make rolling contact on the end of the leaf type spring, the lower cylindrical support body remains stationary and, if it is a rubber roller, can be squashed during severe deflections.
It is therefore an object of the present invention to improve the damping of noises for compound axle assemblies having slidingly supported leaf type springs.